How are behavioral sequences learned and integrated? The proposed research seeks to gain insight into processes underlying serially organized behavior by studying its cognitive development in animals. That strategy eliminates two factors that complicate the study of serially organized behavior in human subjects: language and experience with serial tasks. The investigation of serial learning in animals also provides a comparative perspective of different mechanisms of serially organized behavior. How arbitrary sequences are learned and integrated will be studied through recently developed techniques for training pigeons and monkeys to produce and recall lists of arbitrary stimuli. In the "simultaneous" chaining paradigm, all of the stimuli and opportunities to respond are available simultaneously, a key feature of serial tasks used in verbal learning experiments on human subjects. Only the configuration of list items is changed from trial to trial. Since nothing in the subject's external environment changes as it performs the sequence, exteroceptive feedback cannot explain its ability to produce the required sequence. Nor can proprioceptive feedback: each item appears equally often in each possible position. Recall is trained by a matching- to-successive-samples paradigm in which the subject is required to produce, as a simultaneous chain, lists displayed as the sample. In most instances, lists will consist of digitized color photographs that are displayed on a touch-sensitive video monitor. The nature of representations that mediate sequence production will be studied by determining (1) how list learning changes with successive lists, (2) a monkey s and a pigeon's ability to "chunk" the sequences it recognizes and/or produces, (3) a subject's knowledge of the ordinal position of items in a list, (4) how shifts in the configuration of the list items during the execution of the list effect performance, (5) how learning lists of a particular length effect the acquisition of longer or shorter lists, and (6) whether pigeons and monkeys remember photographs used as list items as unitary objects or as unorganized sets of features. The results of these experiments should provide an animal model of serial learning and an evolutionary perspective for the contribution of verbal mediation to the organization of human serial behavior. The proposed research should also have two important interdisciplinary ramifications. It can provide preparations for studying the neural control of serially organized behavior. The non-verbal serial tasks that will be used with pigeons-and monkeys can also be used with preverbal children in ways that would reveal the contributions that language subsequently makes to the basic cognitive skills needed to perform those tasks.